Method of forming lock nuts



I Api'il 8, 1930. v H. E. BURNS 1,753597 METHOD O bRMING LOCK NUTS Filedma 4. 1927 Patented Apr. 8, 1939 P T orifice HARLEY n. BURNS, oroonunnus onro Mnrrron or FORMING ocK NUTS x Application filed May 4,1927'. Serial m..- 1sae'14.

My invention relates in general to amethod of and apparatus forproducing a nut and more in particular to a novel method of andapparatus for producing the lock nut described in .the co-pendingapplication of Alexander W. MacLean, Serial N 0. 148,568, filed November15, 1926.

One of the principal objects of my invention is to provide an improvedmethod of manufacturing certain types of nuts.

Another object is to provide a method for making the nuts described inthe co-pending application referred to above, economically.

Another object is to provide an improved nut making apparatus adapted toreduce the cost of manufacturing lock nuts. 7 V i To facilitate anunderstanding of my invention it may be said that the nut described inthe co-pending application of MacLean, has recessed top and bottomfaces, the bottom preferably concave, and the top with'a somewhat narrowrecess, or groove, aclapted to close together to grip the threads of abolt, when'thenut isscrewed down tightly enough against a surface topartially flatten the bot tom concave face.

- To manufacture this lock nut I employ bar stock of rectangularcross-section, of substantially the same thickness as thenut to beproduced, butjof less widththan said nut. The nuts are producedcontinuously by a die stamping process which consists in first formingtherecessed upper and lower surfaces, then punching out the holes,cutting the nut fromthe end of the stock and dis charging the unthreadedblank into a suitable receptacle. The tapping and other subsequentoperations may be the same as those employed for producing other typesof nuts.

The invention will be more fully understood after reading the followingdetailed description and referring to the accompanying drawings,wherein:

Fig. 1 is a perspective view of a bar adapt ed to be used for formingthe lock nut de scribed; v

Fig. 2 shows the bar as it is removed from the dies; 7 t 4 Fig. 3 is across-section of the bar shown'in Fig. 4 is a section through the barafter the recessed surfaces are formed therein;

Fig. 5 is a perspective view'of a finished nut; Y I

Fig. 6 is a plan view illustrating'the arrangement of the die blocks andFig. 7 is a fragmentary sectional view along the line of 7-7 of Fig. 6.p

A square headed nut 9, formed in accordance with the co-pendingapplication referred to, and which my invention "aims to produceeconomically and well, is shown in Fig. 5. The top and bottom recessesare shown, as the nut has a" concave bottom 9 and recessed top 9". It isbelieved that the i details of the method by means of which this nut maybeproduced -will be clearer after an understanding of the" apparatuswith which the method maybe practiced. Reference may be hadtherefore,first'to Figs. 6 and 7. Y f

A stationary die block 10 is adapted to cooperate with a reciprocatingpunch block 11 to form nuts from a section of bar stock 12 fed'to thedies by a pair of feed rollers 13. Any ordinary and usual means; may beemployed for operating the dies, and for synchronizing the movementofthe feedrollers 13. In'act ual practicel have used, the well knownfWaterbury' nut machine and have obtained good results therewith, but ofcourse the invention is'not limited to the use of this type of machine;

The die block 10 constitutes the female portion of the die and isstationary. It is pro- I vided with a punch die 16 and a blanking die 17held in positionby a sectional die holder 18. Thedie holder anddies'have a'continuous transverselridge 19v for producing the 'recess'9on the top face of the nut. The sectional die holder fits around thedies 16 and 17 and is held in place by a set screw 21 which is locked bymeans of a suitable nut 22. The male portion of the die comprises aforming die 23, a punch 24, and a blanking die 25, all secured'intheblock 11 in any suitable manner. The forming die 23 forms the lowerconcave surface 9 and forces the stock with such force against the ridge19 as to result in the ridge enteringthe' stockto form maledie block so.that the two the recess 9 Any suitable means is provided forsynchronizing the feed rollers 13 so that they will feed the stock adistance equal approximately to the width of the fin ished nut, so thatat each actuation of the dies, a nut is stamped or cut from the formedend of the bar 12.

The forming die 23 is wider than a nut and its strokes overlap, so thateach section of the bar receives several strokes and at Feast two fullstrokes from this portion of the tool. There is a space between each oneof the three tools in the die so that a section of the bar between eachof the tools which has been operated upon by the immediately precedingtool, and is ready forthe next tool operation.

The blanking die 25 is of square crosssection and fitted to the opening17 in the feortions of the die cooperate to produce afinished blank. 1

' The end of the bar coincides with one edge of the punch, so that ateach operatin'of the die one blankis produced, and the only wastematerial is that trimmed from the longitudinal side edges of the bar.The space-between the dies 24 and 25 may be made either equal to thewidth of a single nut (measured from center to center of the dies) orany multiple thereof. In this way the nuts are continuously produced Iand the finished blanks are forced through the opening 17 where they arereceived by'suitable means (not shown) preparatory to tapping them.

The bar that is employed in the production of the nuts is narrower thanthe finished nut, but during the forming operation the metal pressedfrom the top and bottom of the bar causes a spreading action, therebywidening the bar. The thickness of the bar to begin with, may be thesame or slightly greater than the greatest thickness of the finishednut.

Having described the apparatus, the steps of the method may be madeclearer. A metal bar, preferably a mild steel, of rectangularcross-section, is selected, the bar being as thick as the finished nutbutnot as wide.

The-bar is then formed by a die in a swaging' operation to havearecesson the top and bottom faces thereof, thereby resulted in a formedsection of bar 31. The next step in the continuous sequence ofoperations is piercingthe bar to produce a section of formed and:pierced stock 32, which needs but the single final'blanking operationto be a completed nut blank. All three steps of 'the method areperformed and a completed blank 33 is cut from the formed and piercedbar at each actuation of the dies.

When the nuts are blanked out from the end of the bar, they are trimmedto the proper size, and this results in a small amount of stock in theform of a thin fin 34 being removed around the edges of the nut. It isthistrimming which may cause the nut to be slightly thinner than the barfrom which it is produced, as of course the formed bar is thinner towardthe inside on account of the concave lower face.

When the nuts are produced in this manner they are preferably tumbled inthe usual.

way to remove rough edges, and annealed to remove the strain of work.After this they are threaded on any of the threading machines which arewell known in the art.

As an example of how my nut is produced, a specific example may be givenof a three eighths inch nut that is to be used with a three-eighths inchdiameter bolt. The width of this nut across the flats, is five-eighthsof an inch, while the thickness is five-sixteenths of an inch. Toproduce this nut I employ mild steel bar stock having a thickness ofeleven-thirty-seconds of an inch and a width of one-half inch.

I have found that this method of producing the lock nut described,results in a very strong and'easily handled nut, while at the same timethe cost of production is very low. I am able to make this apparentlycomplicated nut by means of my process, more economically than ordinaryorcommon nuts without locking features.

The method has been described in some detail, and aspecific form ofmechanism illustrated in order to make the invention entirely clear tothose skilled in the art; but I do not restrict myself to the exactfeatures shown, and the invention is limited only by gressively piercingthe formed bar foreachnut blank, and then cutting off each formed andpierced blank from the bar.

' 2. The method offormmg a nut with a transverse recess in a top orbottom face thereof which comprises selecting'metal stock of rectangularcross section, with'less width than the finished blank',"stamping themetal stock to form the recess and widen the stock, the metal of therecess serving to secure the greater width, punching tap holes in theblank,- cutting the blanks from the bar, and threading the blanks. i

3. The method of forming lock nuts of the character described eachhaving recessed top and bottom faces which comprises supplying bar stockof rectangular cross-section, forming the recesses, punching the tapholes therein, and then cutting the nut from the stock, all of saidsteps being performed'on the same stock at the same time, but thesuccessive steps of the operation taking, place at different points 9 te bar, 0 that the rectangular bar stock may be fed, and a continuoussupply of nuts produced.

4. The method of forming lock nuts each having top and bottom recessestherein which comprises supplying bar stock of rectangular crosssection, forming said recesses along the bar by a plurality ofoverlapping blows of suitable forming elements, progressively piercingthe formed bar for each nut blank 10 and cutting off each formed andpierced blank from the bar.

In Witness whereof, I hereunto subscribe my name this 28th day ofFebruary, 1927. HARLEY E. BURNS.

